Method for producing a nut, screw tap for carrying out said method and nut produced according to said method

ABSTRACT

The invention relates to the production of a nut which comprises a drive area ( 2 ) and a clamping area ( 3 ). A bore hole (B) running through the clamping area ( 3 ) and the drive area ( 2 ) is produced in a cylindrical manner. A screw tap ( 15 ) is screwed into the cylindrical bore hole (B) until a predetermined position is reached. Said screw tap is successively provided with the following, when seen in an axial direction from the front side thereof: a centering/cutting section ( 17 ), an adjoining cutting section ( 19 ) which is used to produce a conical internal screw thread section ( 8 ) in the clamping area ( 3 ), and a cutting section ( 21 ) which is used to produce a cylindrical internal screw thread section ( 7 ) in the drive area ( 2 ).

[0001] The invention at hand relates to a method for producing a nut according to the generic term of patent claim 1, a screw tap for performing the method according to the generic term of patent claim 5, as well as a nut produced according to the method according to the generic term of patent claim 15.

[0002] A nut produced by means of massive reshaping is known from DE 195 32 709, which has a drive area for the contact of a tool, an area for attaching on a component, as well as a clamping area that is slotted in longitudinal direction of the nut so that clamping tongues are arranged between two slots each in the circumference direction. Both the clamping area with the slots and clamping tongues, as well as the drive area are produced by means of massive reshaping, such as cold and/or hot extrusion. The nut's internal thread extends along the drive area at a diameter that is constant, and that is reduced at increasing distances from the drive area at least across part of the axial extension of the clamping area.

[0003] The thread of such a nut is usually produced on NC thread cutters, whereby the bore is initially bored cylindrically in the drive area, and conically in the clamping area, and the thread is then cut on the NC cutter. It is clear that such a production method is complicated and expensive. In both processes, the tool movement must occur in conformity of this taper.

[0004] The task of the invention at hand therefore consist of the fact of improving such a method in such a way that it can be performed in a substantially simpler manner, and that nuts can be produced a lot more inexpensively according to this method. Furthermore, a screw tap is to be created for the performance of this method.

[0005] The task named above is solved by means of a method having the characteristics of patent claim 1. The nuts produced by means of the inventive method are marked by the characteristics of patent claim 15. A screw tap for the performance of the method has the characteristics of patent claim 5.

[0006] The substantial advantage of the invention at hand consists of the fact that the complicated steps for conically boring the clamping area, and for inserting an internal thread by means of an NC machine that are required in relation to prior art can be omitted, because a special screw tap for the production of the internal thread is used, which is already conically formed, and is inserted into a bore that is cylindrical in the area of the clamping area and of the drive area. More specifically, the screw tap used in relation to the method according to the invention is embodied in such a way that in addition to a cylindrical thread cutting section for the production of the cylindrical internal thread, it has a special conical thread cutting section in the drive area for the production of the conical area of the internal thread in the clamping area by means of simple screwing in of the screw tap up to a predetermined axial position. It is of particular importance that the screw tap performs merely a simple, straightforward movement.

[0007] Further advantageous embodiments of the invention are contained in the sub-claims.

[0008] The invention and its embodiments are further explained in detail in relation to the figures. They show:

[0009]FIG. 1 a longitudinal section across a nut produced in accordance to the inventive method;

[0010]FIG. 2 a view onto the nut of FIG. 1 from the side opposite of the base;

[0011]FIG. 3 the side view of the inventive screw tap used in relation to the method according to the invention;

[0012]FIG. 4 a section across the screw tap of FIG. 3 along the line VI-VI;

[0013]FIG. 5 an enlarged illustration of the various, and

[0014]FIG. 6 of the screw tap screwed into a nut up to a predetermined position.

[0015] The nut illustrated in FIG. 1 essentially consists of a drive area 2 and a clamping area 3, which are both produced as one piece. On the side facing the base, i.e., on the side opposite of the clamping area 3, the nut has a support area 5. The cylindrical threaded section of the drive area 2 of the nut is identified by 7.

[0016] The drive area 2 has deformations 9 at regular intervals on its radial exterior, which, for instance, form a multitude of edges, and are provided for the contact of the tool, with the aid of which the nut can be pivoted on a bolt, or similar.

[0017] The clamping area 3 that axially joins the drive area 2 is embodied as a core, and is limited in its outer circumference by a conically, or taper shaped lateral area 9, the cone tip of which faces in the opposite direction of the support area 5. The clamping area 3 has several slots, or axially directed recesses 11 that are distributed across the circumference, which axially extend up to the drive area 2. The clamping tongues formed between two slots each are identified by 13. The conical threaded section of the clamping area 3 is identified by 8.

[0018] It has already been pointed out that normally the threaded sections 7 and 8 are produced by initially inserting a cylindrical bore into the drive area 2, and a conical bore into the clamping area 3, and that the cylindrical threaded section 7, and the conical threaded section 8 are subsequently produced with the aid of an NC thread cutter.

[0019] According to the method at hand, the threaded sections 7 and 8 are produced by means of manufacturing only one single axially extending cylindrical bore B in that a screw tap 15 embodied according to FIG. 3 is screwed into the cylindrical bore B from the side of the support area 5 up to a predetermined position in a manner to be further explained as follows. The bore can preferably be produced by reshaping.

[0020] The screw tap 15 has three different threaded cutting sections that are arranged next to each other, viewed in axial direction from the front. The front most centering cutting section 17 is first inserted into the cylindrical bore of the nut and serves for the purpose of centering the screw tap 15 in relation to the cylindrical bore B of the nut, and to pre-cut the thread in the section 21. The cutting section 19 joins the centering cutting section 17, which serves for the production of the conical internal thread of the clamping area 3. In addition to the cutting section 19, a third cutting section 21 is positioned on the side opposite of the centering cutting section 17, which serves the purpose of producing the cylindrical internal threaded section 7 in the drive area 2 of the nut.

[0021] The previously mentioned cutting sections 17, 19, and 21 are illustrated grossly enlarged in FIG. 5. Accordingly, the cutting section 21 provided for the production of the cylindrical internal threaded section 7 in the drive area 2 has teeth, the circular heads 23 and circular legs 25 of which extend in longitudinal direction L.

[0022] The teeth of the cutting section 19 are identified by 26. They are embodied in such a way that their circular heads 27 each are positioned on an intended lateral area, which is tilted at an angle α1 to the longitudinal direction L so that the teeth 26 each have a smaller tooth height toward the front side of the screw tap 15. Preferably, the circular legs 29 of the teeth 26 of the cutting section 19 are also arranged at an angle al in relation to the lateral area that is tilted toward the axial direction L.

[0023] Finally, the teeth 30 of the centering cutting section 17 are created in such a way that their circular heads 31 are positioned on an intended lateral area that is tilted toward the longitudinal axis of the screw tap 15 at an angle α2, whereby the angle α2 preferably is larger than the angle α1. Preferably, the teeth 30 have a teeth height that decreases toward the direction of the front side. Preferably, the respective circular legs 33 of the teeth 30 are also arranged on an intended lateral area at an angle in relation to the longitudinal axis L, which, for instance, corresponds to angle α1.

[0024] According to the inventive method, the screw tap 15 is screwed into continuous, i.e., both in the clamping area 3, and in the drive area 2 cylindrically extending bore of a nut that is centered and clamped in the thread cutter up to an axial position until the cutting section 19 is located at the desired position of the clamping area 3, and the cutting section 21 is at the desired position at the drive area 2. The cutting section 17 protrudes at least partially across the clamping area 3 of the nut. After the mentioned predetermined position has been achieved, the desired conical thread is therefore created in the clamping area 3, and the teeth 22 of the cutting section 21 are mapped exactly in the drive area 2. This condition is illustrated in FIG. 6. Finally, the screw tap 15 is turned back from the predetermined position, and is removed from the nut. The teeth 30 and/or 26 of the cutting sections 17 and 19 serve for precutting of the teeth of the internal thread 7 of the drive area during the screwing in of the screw tap 15 up to the predetermined position. Accordingly, the teeth 30 of the section 17 serve for precutting of the teeth of the internal thread 8 of the clamping area.

[0025] It must be pointed out that the cutting sections 19 and 21 can be dimensioned in such a way that part of the teeth 22 of the cutting section 21 can also be penetrated into the clamping area 3 in the predetermined position so that the created cylindrical threaded section 7 extends beyond the drive area 2, partially into the clamping area 3. In reverse order it is also possible to dimension the cutting sections 19 and 21 in such a way that part of the teeth 26 of the cutting section 19 also penetrate the drive area 2 in the predetermined position.

[0026] It must be further pointed out that the term “conical” means all shapes that taper toward the front side of the screw tap 15. 

1. Method for producing a nut that has a drive area (2) and a clamping area (3), which are produced as one piece, whereby the nut has a bore (B) that is fully engaged in the clamping area (3) and the drive area (2) with an at least partially cylindrical threaded section (7) in the drive area (2), and an at least partially conical threaded section (8) in the clamping area (3), characterized in that the bore (B) fully engaged in the clamping area (3) and in the drive area (2) is produced as a cylindrical bore (B), and that a screw tap (15) is screwed into this cylindrical bore (B) up to a predetermined position. The screw tap (15) has in axial direction, viewed from its front side, a centering cutting section (17), and a subsequently joining cutting section (19) that are arranged next to each other for the production of the conical internal threaded section (8) of the clamping area (3), and a subsequently joining cutting section (21) for the production of the cylindrical internal threaded section (7) in the drive area (2), whereby the cutting section (21) has teeth (22) in the drive area (2) for the production of the cylindrical internal threaded section (7), which extend in longitudinal direction (L), the cutting section (19) has teeth (26) in the clamping area (3) for the production of the conical internal threaded sections (8) that extend at a first angle (al) laterally to the longitudinal direction (L), and the centering cutting section (17) has teeth (30) that extend at a second angle (a2) laterally to the longitudinal direction (L), whereby the screw tap (15) is screwed into the bore (B) up to a predetermined position in a first step. The teeth (22) of the cutting section (21) are mapped in the drive area (2) for the production of the cylindrical internal threaded section (7), and the teeth (26) of the cutting section (19) are mapped in the drive area (2), or in the clamping area (3), respectively, for the production of the conical internal threaded section (8) of the clamping area (3), whereby the screw tap (15) is turned back from the bore (B) of the nut in a subsequent step.
 2. Method according to claim 1, characterized in that in the predetermined position, the teeth (22) of the cutting section (21) is arranged in the entire drive area for the production of the cylindrical internal threaded section (7), and the teeth (26) of the cutting section (19) are arranged in the entire clamping area (3) for the production of the conical internal threaded section (8).
 3. Method according to claim 1, characterized in that in the predetermined position, the teeth (22) of the cutting section (21) in the drive area (2) also partially engage into the clamping area (3) for the production of the cylindrical internal threaded section (7).
 4. Method according to claim 1, characterized in that for the predetermined position, the teeth (26) of the cutting section (19) for the production of the conical internal threaded section (8) of the clamping area (3) also at least partially engage into the drive area (2).
 5. Screw tap for performing the method according to claims 1 to 4, characterized in that when viewed from its front side, it has a centering cutting section (17), and a subsequently joining cutting section (19) that are arranged next to each other for the production of the conical internal threaded section (8) of the clamping area (3), and a subsequently joining cutting section (21) for the production of the cylindrical internal threaded section (7) in the drive area (2), whereby the teeth (22) of the cutting section (21) for the production of the cylindrical internal threaded section (7) in the drive area (2) extend in longitudinal direction (L) of the screw tap (15), the teeth (26) of the cutting section (19) for the production of the conical internal threaded section (8) in the clamping area (3) extend along a line tapering toward the front side, and the teeth (30) of the centering threaded section (17) extend along an additional line that tapers toward the front side.
 6. Screw tap according to claim 5, characterized in that the teeth (22) of the cutting section (21) have circular heads (23) and circular legs (25) in the longitudinal direction (L) of the screw tap (15) for the production of the cylindrical threaded section (7) of the drive area (2).
 7. Screw tap according to claims 5 or 6, characterized in that the teeth (26) of the cutting section (19) for the production of the conical threaded area (8) of the clamping area (3) have circular heads (27) that are positioned on an intended lateral area that is tilted at a first angle (al) to the longitudinal direction (L) of the screw tap (15).
 8. Screw tap according to claim 7, characterized in that the tooth height of the teeth (26) of the cutting section (19) for the production of the conical threaded section (8) of the clamping area (3) increases in size toward the front side of the screw tap (15).
 9. Screw tap according to claim 7, characterized in that the circular legs (29) of the teeth (26) of the cutting section (19) for the production of the conical threaded section (8) of the clamping area (3) are arranged on a lateral area that is tilted at a first angle (α1) in relation to the longitudinal direction (L) of the screw tap.
 10. Screw tap according to one of the claims 6 to 9, characterized in that the teeth (30) of the centering cutting section (17) has circular heads (31) that are positioned on an intended lateral area that is tilted at a second angle (α2) to the longitudinal direction (L) of the screw tap (15).
 11. Screw tap according to claim 10, characterized in that the second angle (α2) is larger than the first angle (α1).
 12. Screw tap according to claims 10 or 11, characterized in that the teeth (30) of the centering cutting section (17) have a tooth height that decreases toward the front side.
 13. Screw tap according to one of the claims 10 to 12, characterized in that the circular legs (33) of the teeth (30) of the centering cutting section (17) are positioned on an intended lateral area that is tilted at a third angle in relation to the longitudinal direction (L) of the screw tap (15).
 14. Screw tap according to claim 13, characterized in that the third angle corresponds to angle (α1).
 15. Nut, produced according to the method according to one of the claims 1 to 4, characterized in that it contains a clamping area (3), a drive area (2) that is connected to the clamping area (3) in one piece, and support area (5) that is arranged on the side of the drive area (2) that is opposite of the clamping area (3), whereby a cylindrical internal threaded section (7) extends at least partially across the drive area (2) in a bore (B) in the area of the drive area (2), and a conical internal threaded section (8) is arranged that extends at least partially across the clamping area (3) in the clamping area (3), which are produced in one step by screwing in a screw tap (15) into a cylindrical bore (B) according to one of the claims 5 to 13 up to a predetermined position, whereby the clamping area(3) is embodies in the shape of a core, and is limited in its exterior circumference by a conical, or taper shaped extending lateral area (9), the tip of which faces the opposite direction of the support area (5), and whereby the clamping area has several axially positioned recesses (11) that are distributed across the circumference, which axially extend at least up to the drive area (2).
 16. Nut according to claim 14, characterized in that the drive area (2) has deformations (9) at regular intervals on the radial exterior, on which a tool can be placed for turning out of the nut on a bolt. 